1. FIELD OF THE INVENTION
The invention relates to oil injected rotary compressors, and more particularly to a method of draining oil from a transmission housing, or other chamber, of a compressor from which collected lubricating oil is required to be raised and returned to the rotor chambers.
2. PRIOR ART
When the transmission housing of a gas compressor has been arranged such that its sump is lower than the compressor rotors it has been usual practice to use a mechanical pump to lift the oil out of the transmission housing and return it to the compressor, the lifting action being caused by the creation of a depression or sub-atmospheric pressure at the pump inlet by the pump.